1. Field of the Invention
This invention relates to integrated circuits, and in particular, to the identification of integrated circuits which have been processed in a particular manner, for example, to identify those integrated circuits which have been repaired by having redundant portions connected.
2. Description of the Prior Art
The size of very large scale integrated circuit products is increasing continuously. At the same time improvements in process technology are enabling the fabrication of smaller components on integrated circuits, and therefore even more devices on a given size integrated circuit. To improve yields some integrated circuits are now designed with redundant features which may be utilized should other features be found non-functional. These redundant circuits replace defective sections of the integrated circuit so that a fully functional product may be sold after the integrated circuit is appropriately connected.
One major problem in the fabrication and sale of such devices is that the repair may be transparent to the user after the integrated circuit is packaged. Some high reliability integrated circuit users prefer not to use redundant features on the integrated circuit because of their belief that the reliability of such redundant features is questionable. Because the customer may not desire the redundant features, the manufacturer of such circuits may hesitate to include the features on a given circuit.